This invention relates to a head suspended from a top drive for use in sequentially dropping balls and plugs into a liner suspended from the head. More particularly, it relates to the use of such equipment in cementing the liner within the outer casing, such as disclosed for example in Provisional Application No. 60/292,049 filed May 18, 2001, and assigned to the assignee of this application, wherein the one or more balls and wiper plugs are to be dropped onto a seat within the liner to actuate certain parts for the purpose of hanging the liner in the outer casing, followed by the dropping of pump down plugs through the liner for pumping cement beneath them into the annulus between the liner and outer casing.
In previous heads of this type, the balls and wiper plugs were mounted in individual manifolds with each having an opening onto a bore leading to the equipment to be actuated. As will be appreciated, this increased greatly the vertical height of the equipment beneath the top drive, thus making it that much more inaccessible, not only during loading and releasing of the balls and pump down plugs, but also in obtaining visual access to the interior of each manifold in which the plugs and balls were located.
U.S. Pat. Nos. 6,182,752 and 6,206,095 allege to solve the problem of excess height by means of heads of such construction as to permit the balls and plugs to be mounted and dropped from essentially the same vertical location beneath the top drive. Nevertheless, their construction is complicated and requires large internal rotating parts which increased the possibility of leakage and other need for repair.
It is therefore the general object of this invention to provide such a head in which the balls and plugs are mounted on generally the same level, but which does not include the large rotating parts and other mechanisms increasing the risk of repair and replacement.
This and other objects are accomplished, in accordance with the illustrated embodiments of this invention, by a housing having an inlet adapted to be fluidly connected in line with the lower end of a top drive, an outlet generally aligned with the inlet, and passages extending downwardly within the housing at circumferentially spaced locations. Each passage has an upper end opening to the side of the inlet and a lower end connecting with the outlet, and lateral openings in the housing each connect the inlet with a passage. A closure member is removably mounted in the upper end of each passage to permit a ball or plug to be installed therein, and plug valves are mounted in the housing each for opening and closing an opening beneath the lateral passage connecting thereto so as to support the ball or plug, when closed, and permit it to pass therethrough, when open. Circulating fluid may pass downwardly through an open passage when a ball or plug is not in the passage.